This invention relates to a sparger for use in fermentation and tissue culturing vessels and in particular, to a sparger for use in microcarrier fermentation systems.
The use of cell culturing techniques are widely known, and are vital to the study of animal cell structure and for the production of important medical material such as hormones, enzymes, antibodies, vaccines, etc. When using tissue and microcarrier cell culturing techniques, the cells are ultra-fragile in nature, and easily damaged during growth. The culturing of anchorage-dependent cells has proved particularly difficult and the use of micorcarriers for this purpose has been developed. In microcarrier cultures, cells are grown as single layers and sometimes multilayers on a surface of microcarriers, generally small spheres, which are in turn suspended in a culture medium by gentle agitation. A detailed description of microcarrier cell culture principles may be found in the book "Microcarriers Cell Culture: Principles and Methods", Pharmacia Fine Chemicals, Sweden, December 1981.
It is important to provide air to microcarrier fermentation systems so as to provide oxygen to the cells. Additionally, it is also important to provide other gases to the system. A major problem, however, is that aeration is generally achieved by conventional means such as bubbling the gases through the fluid by placing a delivery tube in the fluid with an exit near the bottom thereof. This bubbling creates a form which is troublesome to most fermentation processes and can be fatal in microcarrier tissue culture processes.
A process has been developed to diffuse the air or other gases through a silicone rubber tube. However, the tube must have a large surface area and consequently, insufficient oxygen is transmitted to the medium.
It has also been proposed to deliver sparged air using a conventional tube to a point at the bottom of a cylindrical screen. The bubbles pass through the liquid within the screen which keeps the microcarriers away from the bubbles, thereby reducing the deleterious effects of foaming. This arrangement, however, has not proved satisfactory.
Accordingly, it is desirable to provide an improved sparger for use in microcarrier fermentation systems.